Electrical Transients

Problem 406: In an RL circuit, Kirchhoff's Law gives the following relation: E = L di/dt + Ri where: E = supply voltage (200 volts), R = resistance (20 ohms), L = inductance (1 henry), t = time in seconds, i = current in amperes. If i = 0 when t = 0, find i when t = 0.02 second.

Problem 407: In an RL circuit, Kirchhoff's Law gives the following relation: E = L di/dt + Ri where: E = supply voltage (200 volts), R = resistance (20 ohms), L = inductance (1 henry), t = time in seconds, i = current in amperes. If i = 0 when t = 0, find i after a long time.

Problem 408: A 6.0 H coil whose resistance is 12 ohms is connected in series with a 24 ohms resistor and to a 144 V battery and a switch. The switch is closed at t = 0. Determine the time constant of the circuit.

Problem 411: A coil has a resistance of 10 ohms and a time constant of 1 second. If the coil connected across a steady potential of 24 V, how much is the current after 2 ms?

Problem 415: A 6.0 H coil whose resistance is 12 ohms is connected in series with a 24 ohms resistor and to a 144 V battery and a switch. The switch is closed at t = 0. Determine the current at t = 0.1 second.

Problem 419: A resistance of 100 k\(\Omega\) is connected in series with a 100 \(\mu\)F capacitor. If the combination is suddenly connected across a 125 V DC source, determine the current one second after the switch is closed.

Problem 423: A 20-ohm resistance R and a 0.001 farad capacitance C are in series. A direct current voltage E of 100 volts is applied across the series circuit at t = 0 and the initial current i(0) = 5 A. The applicable differential equation is: R(di/dt) + i/C = 0. Solve the differential equation and determine the resulting current i(t) at t = 0.01 second.

Problem 424: A series RC circuit consist of R = 2 M\(\Omega\) and an uncharged capacitor C = 5 \(\mu\)F. The circuit is connected across a 100 VDC source at t = 0. Determine the voltage across the resistor 5 seconds later.

Problem 426: In a circuit consisting of a resistance, R ohms, in series with a capacitance, C farad, and connected to a DC source with emf E volts, the electrical charge, Q coulombs and the current i, amperes, maybe determined by solving the simultaneous equations: Ri + Q/C = E and I = dQ/dt. If R = 20 ohms, C = \(250\times10^{-6}\) farad and E = 100 volts, find i after a long time.

Problem 427: An 80 \(\mu\)F capacitor in series with a voltmeter of 10,000-ohm resistance is connected suddenly across a 100-V supply. How long will it take for the voltmeter to register 15 V?

Problem 429: An 80 \(\mu\)F capacitor in series with a 1000-ohm resistor is connected suddenly across a 110 V DC supply. Find the value of the current after one time constant.

What value of R is needed with a 0.05 μF capacitor for an RC time constant of 0.02 sec?

A capacitor of 100 micro farad is connected in series with a resistance of 1000 ohms. The time constant of the circuit is

A coil has a resistance of 5 ohms and inductance of 1 H. At t = 0 it is connected to a 2 V battery. Find the rate of rise of current when i = 0.2 ampere.

Calculate the time taken by the capacitor of 1 μF and in series with a 1 MΩ resistance to be charged up to 80% of the final value.

An inductance of 40 mH is connected in series with 300 ohms resistance, At t=0, the energy stored is 0.96 microjoule. Find the current at t=0.

A coil of inductance 10 H and resistance 2 ohms is supplied at 20 v, Find the average emf induced when the circuit is opened if the current fails to zero in 0.5sec.

A time of 10 milliseconds is required for the current on a series RL dc circuit to reach 90% of its final steady state value. What is the time constant in seconds for the circuit?

A capacitor is charged by a dc source through a resistor of one megohm. If in one second, the potential difference across capacitor reaches 80% of its final value, calculate its capacitance.

A current of 20 A is flowing in an RL series circuit the instant before the switch is opened. If R = 10 Ω and L = 10 H, find the current after 3 seconds have elapsed.